Abstract Interstitial cystitis/bladder pain syndrome (IC/BPS) is a debilitating chronic pelvic pain condition associated with urinary urgency and frequency that affects as many as 7.9 million women in the United States. The pathophysiology of IC/BPS remains incompletely understood but is thought to involve both central and peripheral disturbances in the processing of pain and viscerosensory signals. Pelvic floor dysfunctions likely contribute to the pain experienced by affected women, as myofascial pain and hypertonic pelvic floor dysfunction coexist in 85 % of patients with IC/BPS and other chronic pain syndromes. It was also found that myofascial pain was demonstrated in 78.3% of IC patients with at least one myofascial trigger point (TP). Current treatment modalities aimed at pelvic floor relaxation, including TP injection and physical therapy, have shown positive results on improving the syndromes; however, assessment of pelvic floor TP and hypertonicity is subjective, qualitative and operator-dependent. Identification of TPs through digital palpation depends on the therapist's subjective perception of what constitutes an abnormality and there has been disagreement between expert urologists and therapists regarding the presence or absence of TPs, their locations and degrees of abnormality. No agreement exists upon protocol or standardization of the pelvic exam. Objective measures of pelvic floor muscle (PFM) functions in IC/BPS patients are lacking, which would otherwise help elucidate the contribution of pelvic floor dysfunctions to the pathophysiology of IC/BPS and provide an objective phenotypic characteristic of IC/BPS. The goal of this proposal is to develop an objective and quantitative tool to standardize the characterization of pelvic floor dysfunction in IC/BPS using the most recent advances in high density (HD) surface electromyogram (EMG) techniques. This research represents the first effort to comprehensively and quantitatively assess the hypertonicity of the PFMs associated with IC/BPS, by taking advantage of the most recent advances in HD surface EMG recording and signal processing techniques. The PI has successfully captured HD surface EMG signals from the PFM of 10 young healthy female subjects using multi-channel EMG probes, see preliminary data. In this proposal, the innovation will be applied to IC/BPS patients. The patient-specific hypertonicity severity map, trigger point map and innervation zone (IZ) map of PFMs objectively determined with HD surface EMG will help understand the underlying PFM dysfunction in IC/BPS. The proposed hypertonicity severity mapping technique can also serve as a novel tool to objectively and quantitatively evaluate the hypertonicity the PFMs in patients with IC/BPS. The TPs and IZs of the PFM will be compared in order to better understand their physiological connections and further better understand the pathophysiology of IC/BPS. The TP and IZ detection techniques can also be utilized to improve current therapeutic approaches such as TP injection and myofascial physical therapy by providing objective injection or training targets.